Furnace



July 17, 1934. J, L, MQFA'RLAND FURNA'QE Filedoct/jl. 1932 lA/66Nd His Attorneg.

James LJ. McFarlund,I

42 20 Inventor:

A Fig-5.

Patented July 17, 1934 PATENT GFFCE FURNACE James L. McFarland, Schenectady, N. Y., assigner to General Electric Company, a corporation of New York Application October 1,

6 Claims.

My invention relates to furnaces, more particularly to conveyor furnaces, and has for its object the provision ofy a simple and reliable conveyor furnace.

My invention is especially applicable to conveyor furnaces such as used in the baking or firing of vitreous enamel and of the type wherein an elongated heating chamber is provided Ywith one end closed and the other end'openedfor 10 the ingress and egress of the work. The articles to be heated are carried on an endless conveyor which is supported from a track mounted on the roof of the furnace. This conveyor extends through the furnace in two substantially parallel lengths which are joined by bends at Vthe closed and opened ends of the chamber.

Suitable driving means is provided for the conveyor such driving means being located outside ofthe furnace. Considerable dimculty has been experienced by reason of theY binding of the conveyor on the track at the inner ends at the bend due to the fact that the'propulsive force for the conveyor must be applied as a tension in one of the parallel lengths of the conveyor itself which tends to cause lateral displacement of the conveyor at the bend and therefore binding at that point. This lateral displacement' is furthermore of disadvantage by reason of the fact that the track is ordinarilyv mounted in a 130 separate compartment on the roof of the furnace in order that the conveyor may be operated at a lower temperature than that in the furnace itself. Communication is had with the furnace chamber through a slot in the roof through which hanger members for the work depend. Any lateral displacement of the conveyor therefore tends to cause rubbing of the hanger members on the sides of the slot with consequent wear vand sluggish action,

In carrying out my invention I provide'a turn'- wheel at the inner end of the furnace around which the chain conveyor passes and by means of which the conveyor is secured against lateral movement. By means of this construction the power required to drive the conveyor is greatly decreased and more uniform and dependable operation is obtained. For a morev complete understanding of my present invention reference should be had to the accompanying drawing in which Fig. l is a side elevationview partially in section of an electric enameling furnace embodying my invention; Fig.

2 is a fragmentary plan view partially in section of the furnace shown in Fig. l; Fig. 3 is a sectional View taken along the line 3-3 ofV Fig.

1932, Serial N0. 635,760

2 looking in the direction of the arrows; while Fig.` 4 is an enlarged view partially in section showing details of construction.

Referring to the drawing I have shown my invention in one form as applied to an electrically heated furnace of the type used in baking or ring vitreous enamel but it will be understood that my invention is not limited as to the source of heat nor to the purpose for which the furnace is applied. AThefurnace is furthermore shown as of the type ldescribed and claimed in Patent No. 1,830,548 to C. L. Ipsen and J. L. McFarland. It comprises heat refractory walls 10 forming an elongated heating chamber, the walls being formed of suitable heat refractory bricks and enclosed in an outer metallic casing 11. The furnace walls are supported on a metallic framework comprising a plurality of vertically arranged I-beams 13 at each side arranged in pairs having theirr upper ends connected by horizontal L'beams 15 extending across the top of the furnace. One end of the furnace, as shown the left-hand end, is closed by wall 16 and this end is elevated and further supported on horizontal I-beams 1'7 extending underneath the furnace. This elevated closed end of the furnace serves to entrap the heated air while the opposite lower end remains open for the passage of the articles to be heated into and out of the furnace. In the raised end portion is a central wall 18 made of suitable heat refractory material which divides that portion into two chambers connected together through the passage remaining between the inner end of this wall, i. e., the left-hand end as observed in Fig. 1 of the drawing, and the closed end of the furnace. The articles to be heated may therefore be passed continuously into the furnace along one side of the central wall 18 across the closed end and out past the other side of the wallf18. The inclined portion 19 of the heating chamber serves as a heating exchange chamber wherein heat is given up from the hot articles passing out of the furnace along one side of this chamber to the cold incoming articles on the opposite side of this chamber.

The roof wall of the furnace is provided with a lJ-'shaped slot 20 having its two parallel straight portions extending in substantially parallel relation throughout the length ofthe furnace and its curved portion 200. extending across the closed end.v This curved portion 20cVV of the slot is preferably formed as an arc of a circle having its center midway between the two parallel lengths of lthe slot.' The slot is provided for hangers 21 having their upper ends pivotally secured to trolleys 22 mounted on a track 23 shown as an I-beam. This track is mounted directly above the slot 20 and is identical in shape with the slot. The hangers extend downward through the slot into the heating chamber and carry racks 24 on their lower ends on which the articles 25 to be heated are supported. The track and conveyor mechanism of which the trolleys and hangers form a part are enclosed in a suitable metallic cap member mounted on the top of the furnace, this member being constituted by inverted channel member 26 and 27 along the parallel lengths of the slot which channels `ioin an enlarged metallic enclosure 28 at the closed end of the furnace. rIhis cap member comprising the members 26, 27 and 28 forms a support for the conveyor mechanism and the roof wall of the furnace, the cap member being in turn secured to the supporting beams 15.

As shown, the various trolleys 22 of the conveyor are connected together by means of bendable connecting means, shown as a linked chain 29, the trolleys being spaced suitable distances apart and each trolley carrying a hanger 21 for the charge. The conveyor is driven by suitable means on the exterior of the furnace adjacent the open end which means applies a. tension to one side of the conveyor for example, to the chain 29. Consequently there is a tendency for the trolleys to bind on the track in going around the bend and furthermore for the hangers to rub against the sides of the slot 20. In order to facilitate the movement of the conveyor around the bend I have provided a turnwheel 30 having substantially the same radius as the track and slot. This turnwheel is mounted in the enclosure 28 on suitable ball bearings 31 and 31a having their axis of rotation perpendicular to the plane of the conveyor at that point and passing through the center of curvature of the portion 20a of the slot. The bearings are mounted in a hub 32 which is in turn supported by the relatively heavy plate 32a forming the top of the enclosure 28.

Extending below the turnwheel 30 is a metallic spider member 33 which forms a support for that section of the roof wall of the furnace which is beneath the turnwheel. This spider member is provided with two arms 34 and 35 which are secured to the supporting plate 32a, While it is supported centrally by means of a rod 36 passing through it and through an aperture or bore provided for it in the center of the turnwheel and the turnwheel bearing, the rod being secured at its top to a cap 37. This spider member 33 is provided with a plurality of arms 38 around the bend of the slot which arms support arcuate metallic plate members 39 defining the inner edge of the slot. Outer metallic members 39a are provided to define the outer edge of the slot, these members being secured to the Walls of the enclosure 28. The portion of the roof wall of the furnace just below the turnwheel is secured to the spider member by means of bolts 40 so as to be supported by the spider member. Preferably, the construction of the roof wall itself is substantially as described and claimed in my Patent No. 1,852,816 dated April 5, 1932.

The periphery 41 of the turnwheel 30 is on the same level as the chain 29 of the conveyor, and the turnwheel is of such size as to engage the chain around the bend and thereby hold the conveyor in position with the hangers midway of the slot. It will be observed that the periphery of the turn wheel is substantially coincident with the inner edge of the slot.

As shown in Fig. 4 the members 39 and 39a are each provided with a pair of spaced upright ridges or projections adjacent the slot opening whereby channel shaped receptacles 42 and 43 are provided along the sides of this slot for the collection of any dirt or foreign material which is released by the abrasive action with the sealing plates 44. These sealing plates 44, as shown in Fig. 3, are coextensive with each link of the chain. They are pivoted together and mounted at such distance below the chains as to ride on the two outer and higher ridges 45 and 46 of the members l39 and 39a. As shown, the plates are supported on extensions of the pivot pins of the chain and the plates are preferably loose on the pins as shown so as to rest by gravity on the ridges 45 and 46. The plates provide a heat seal for the slot.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A furnace comprising walls forming an elongated horizontally extending heating chamber, a plurality of conveyor members for passing articles to be heated through said chamber, a U-shaped track for said conveyor members provided with substantially parallel lengths joined by a bent portion, means connecting said conveyor members together in spaced relation with each other along said track so as to form a conveyor, and a guide member pivotally mounted adjacent the bent portion of said track so as to engage said connecting means around said bent portion and thereby prevent lateral movement of said conveyor members in passing around said bent portion.

2. A furnace comprising walls forming an elongated horizontally extending heating chamber having one end open and its other end closed, a plurality of conveyor members for passing articles to be heated through said chamber, a U-shaped track for said conveyor members provided with substantially parallel lengths joined by a bent portion at said closed end, means connecting said conveyor members together in spaced relation with each other around said track so as to form a conveyor, and a guide member having substantially the same radius as said bent portion pivotally mounted adjacent said bent portion so as to engage said connecting means around said bent portion and thereby prevent lateral movement of said conveyor members in passing around said bent portion.

3. A furnace comprising walls forming an elongated horizontally extending chamber having one end open and its other end closed, a plurality of conveyor members for passing articles to be heated through said chamber, a U-shaped track for said conveyor members having substantially parallel lengths extending throughout said chainber connected by a bent portion at the closed end of said chamber, means connecting said conveyor members together in spaced relation along said track so as to form an endless conveyor, said connecting means being arranged to be driven so as to move said conveyor members through said furnace and a turnwheel mounted adjacent said closed end so as to be engaged by said connecting means to prevent lateral movement of said conveyor members in passing around said bent portion.

4. A furnace comprising walls forming an elongated horizontally extending heating chamber having Qne end open and its other end closed, the

roof Wall of said chamber being provided with a U-shaped slot, and conveyor mechanism comprising a U-shaped track mounted above said slot on the exterior of said chamber, conveyor members for the articles to be heated mounted on said track and hanging downward through said slot into said chamber, a chain connecting said conveyor members together in spaced relation to form an endless conveyor, a turnwheel mounted above said roof wall having its periphery substantially locally coincident with an edge of said slot at the bend thereof so as to be engaged by said chain and thereby hold said conveyor members centrally of said slot and an enclosure member for said slot and said conveyor mechanism.

5. A furnace comprising Walls forming an elongated horizontally extending heating chamber, a slot in the roof Wall of said chamber provided with a curved portion, an enclosure member for said slot forming a support for the roof Wall of said chamber, a conveyor in said enclosure member, a turnwheel in said enclosure member for said curved portion of said conveyor and a support for said roof Wall secured to said enclosure member and extending beneath said turnwheel.

6. A furnace comprising Walls forming an elongated horizontally extending heating chamber having one end open and its other end closed, the roof wall of said chamber being provided with a U-shaped slot, and conveyor mechanism comprising a U-shaped track mounted above said slot on the exterior of said chamber, conveyor members for the articles to be heated mounted on said track and hanging downward through said slot into said chamber, a chain connecting said conveyor members together in spaced relation to form an endless conveyor, an enclosure member forming a support for said conveyor mechanism and the roof wall of said chamber, a turnvvheel for said conveyor mechanism mounted in said enclosure member adjacent the bend in said slot, said turnwheel being provided with a bearing having a bore, a support for said roof Wall secured to said enclosure member and extending beneath said turnwheel and means passing through said bore for securing said support.

JAMES L. MCFARLAND. 

